/* */ #include <iostream> #include <vector> using namespace std; const int MOD = 1000000007; void print(const vector<int>& vec) { for (int i=0; i<vec.size(); i++) { cout << vec[i] << ' '; } cout << '\n'; } int main() { int n; cin >> n; vector<int> w(n+1, 0); int max_x = 0; for (int i=0; i<n; i++) { cin >> w[i]; max_x += w[i]; } vector<int> res; // cout << max_x << '\n'; // iterate through possible x for (int x=1; x<=max_x; x++) { // cout << "x = " << x << '\n'; // fix x w[n] = x; max_x += x; // print(w); vector<int> dp(max_x + 1, 0); dp[0] = 1; // add everything to knapsack for (int i=0; i<=n; i++) { for (int s=max_x; s>=w[i]; s--) { dp[s] += dp[s-w[i]]; if (dp[s] >= MOD) dp[s] -= MOD; } } // print(dp); bool friendly = true; for (int i=0; i<=n; i++) { if (!friendly) break; int max_s = max_x - w[i]; if (max_s%2 != 0) { // cout << max_s << " is not even, cannot split\n"; friendly = false; break; } // remove w[i] // cout << "removed " << w[i] << '\n'; for (int s=w[i]; s<=max_x; s++) { dp[s] -= dp[s - w[i]]; if (dp[s] < 0) dp[s] += MOD; } int half = max_s / 2; if (dp[half] > 0) { // cout << "We can split " << max_s << " in half\n"; } else { // cout << " We cannot split " << max_s << " in half\n"; friendly = false; } // print(dp); // add back w[i] for (int s=max_x; s>=w[i]; s--) { dp[s] += dp[s - w[i]]; if (dp[s] >= MOD) dp[s] -= MOD; } // cout << "added back " << w[i] << '\n'; } if (friendly) { // cout << x << " is friendly\n"; res.push_back(x); } // print(dp); max_x -= x; } cout << res.size() << '\n'; for (int i=0; i<res.size(); i++) { cout << res[i] << ' '; } cout << '\n'; return 0; }